DE2343841A1 - METHOD AND DEVICE FOR THE REDUCTION OR ELIMINATION OF IMPROPERITY IN MOTOR VEHICLE TIRES - Google Patents

Description

Patent attorney Dipl.-Phys. Gerhard Lied! 8 Munich 22 Steinsdorfstr. 21-22 Tel. 298462

C 6151

Gebr. HOF] ViANN K. G., machine factory 61 Darmstadt, Pallas pointed street 72

Method and device for reducing or eliminating irregularities in motor vehicle tires.

The invention relates to a method for reducing or eliminating of irregularities in motor vehicle tires, in which the forces generated when the loaded tire is stationary or rolling is measured and depending on the angular positions and the magnitude of the forces on the tire, material is removed and a device to carry out this process, which force measuring devices and material removal means, in particular in the form of grinding wheels, which are controlled by the force measuring devices ^.

N / Br.

509812/0066

Tires that stand or roll on a surface generate forces in radial, lateral and tangential directions. By superimposing the individual forces and by the fact that the tangential, lateral and radial forces do not attack exactly in the center of the tire's contact patch, there are also moments that are around the vertical axis of the tire and act around the perpendicular to the vertical axis.

Methods and devices have now become known (German Offenlegungsschrift 1 779 156) in which irregularities on the motor vehicle tire in the radial direction, the so-called radial force fluctuations on the rotating motor vehicle tire by themselves Repetitive grinding processes, which are usually carried out in the outer tread areas, the so-called tire shoulders will be reduced. When using several grinding wheels

are these simultaneously according to the angular position of the radial Force fluctuation maxima brought to the tire.

A method is also known from the German Offenlegungsschrift 1 755 329 in which pressure differences are measured for each side of the tire and corresponding amounts of material are taken from each side of the tire as a function of the pressure differences. This is also intended to avoid differences in axial pressure.

The known method does not take into account the lateral forces which occur when a person is standing or rolling under load. Motor vehicle tires occur. In the known methods, only the forces occurring in the radial direction are measured and the grinding processes are controlled accordingly. However, it has been shown that lateral forces can be greater

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as radial forces and that by balancing the radial forces the lateral forces can still be increased.

The object of the invention is therefore to provide a method 'and to show a device for reducing or eliminating irregularities in motor vehicle tires, in which the individual Forces and moments that emerge during the test are taken into account during material removal.

This object is inventively achieved in that both the lateral as well as radial forces are measured and that in response to these forces both a performance-oriented than in the lateral direction and in the radial direction of removal of material ^1:

In the method according to the invention, a in an earlier patent application The described method for testing the quality of motor vehicle tires is used in which, with the aid of measurements of the forces in the radial, tangential and lateral directions, the moments acting in the contact area of the tire are also determined will.

In the method according to the invention, the instantaneous values of the radial force fluctuations and the lateral force fluctuations become the Vector sums are formed and the material removal devices acted upon separately according to the size and the angle differently.

The method according to the invention can be carried out elegantly and simply by depending on the direction of the vector sum of the lateral and radial forces one in either radial

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or material removal oriented in the lateral direction takes place, the . is reinforced compared to the other direction. The increased material removal oriented in one direction is preferably around that Double stronger than the other way. This can preferably be carried out in such a way that after every or every second tire rotation the approximately double reinforced material removal takes place.

A continuous measurement of the instantaneous values of both the lateral and the radial forces is also carried out during the material removal carried out.

Another possibility for carrying out the method according to the invention is that the material is removed in one of the two directions (lateral, radial) until the forces in the in the other direction a significant influence as a result of the material removal experience and that when such a change in the forces occurs in the other direction, the material removal occurs takes place correspondingly offset points of the motor vehicle tire. When material removal is oriented in one direction (lateral or radial) is completed, the compensation takes place in the other direction.

In the device of the type mentioned above, the above The object is achieved according to the invention in that two grinding wheels are provided which can be placed on the tire shoulders and can be controlled separately according to the determined instantaneous values of the lateral and radial forces. In the invention thus two adjustable grinding devices are provided, which can be acted upon separately. For structural reasons these grinding devices can be offset against each other on the

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fenestration be provided. The material is removed here at the tire shoulders, whereby the angular position of the grinding wheels to the tire surface can be variable.

Several removal devices can also be provided, wherein the removal devices can be used either to reduce the radial force fluctuations or the lateral force fluctuations. Furthermore, the removal devices can be arranged at any point on the tire circumference.

The peak-to-peak values of the force fluctuations or the first to nth order harmonics can be used to control the grinding devices by the force measuring devices.

The invention shows a method for improving the quality of tires, in particular motor vehicle tires, in which not only the forces acting in the radial direction, but also the forces acting on the tire in the lateral direction and the moments are taken into account and a corresponding material removal takes place. In the invention, the force fluctuations and the moments that occur are reduced quickly and accurately to a permissible tolerance range. When carrying out the invention, the quality improvement takes place either in that only the force fluctuations are reduced or at the same time that the additional torques are also taken into account.

Can also be used to improve the quality of Kxafifalir vehicle tires according to the invention, the so-called cone effect can be taken into account. This occurs e.g. with radial tires due to the eccentricity of the Belt in the tire. When measuring the cone effect, the

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Tire rotated in two directions and the static side force components measured and saved with subsequent arithmetic averaging. The stored measured values are then fed to a comparison device which decides whether compensation is necessary.

The accompanying figures serve to further explain the invention. Show it:

1 shows the vectors of the lateral force fluctuation and the radial force fluctuation as well as the resulting vector of the force fluctuation;

2 shows the static side forces which are used to determine the cone effect can occur with different directions of rotation and

Fig. 3 is a block diagram of a measuring device with which the inventive Procedure can be carried out.

In FIG. 1, the vector of the lateral force fluctuation is in the X direction SKS and the vector of the radial force fluctuation RKS in the Y-direction. The one resulting from these two force fluctuation vectors The vector forms one with the vector of the radial force fluctuation

SKS angle α, which is given by the mathematical relationship tan a =. At the same time, this indicates whether the angle α is mathematically in the first or fourth quadrant. With the boundary conditions a = 90 °, RKS = 0, so that material removal or grinding takes place "k-axin, which is only oriented in the lateral direction. If α = 0, SKS - 0, with only oriented in the radial direction Material removal or grinding takes place.

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The determination of the measured values takes place continuously, so that the material removal means or the grinding devices are always controlled according to the instantaneous values. There is an angle α = 45 ° - 90 °, this means that the radial force fluctuations RKS are smaller than the lateral force fluctuations SISS. The tire must then be grinded on one side in the lateral direction. Accordingly, depending on the determined angular value for α, the one grinding device with a stronger feed rate driven against the tire than the other grinding wheel, the difference in the feed rate being greater the greater the angle α goes towards 90 °. In a preferred manner, one proceeds in such a way that the one grinding device or grinding wheel is stronger by a factor of 2 is driven on the tires than the other, which means that good values can be achieved.

If the range of the angle α is between 0 ° and 45 °, the radial force fluctuations are RKS greater than the lateral force fluctuations SKS. The material removal then takes place predominantly in a radially oriented manner Direction. This is carried out in that the two grinding wheels are brought up to the tire with the same feed rate.

The increased feed or double feed of the one grinding device against the tire can be done by anyone, preferably everyone. second tire rotation. Because due to the different rubber thicknesses caused by deposits in the tire no fixed function between the force fluctuations exist in the radial direction and in the lateral direction is preferred Continuous measurement and verification of the influence of the erosion on the quality of the tire.

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In the second type of implementation of the method according to the invention, the grinding devices are controlled according to separate measuring processes; that is, the radial and then the laterally oriented reduction of the irregularities or static forces of the tire takes place first. In order to determine the mutual influence or reaction during the grinding process that has just been carried out, a continuous measurement is also carried out. If, for example, the maximum force fluctuation occurring in the radial direction is reduced, the effects on the lateral force fluctuations are measured at the same time. If the measurement result is in the desired direction, that is, if the radial force fluctuations are reduced, there is no or only a slight influence on the lateral force fluctuations, the grinding can continue at this point until the radial force fluctuations are within the tolerance range. If, however, there is an increase in the side force fluctuations, the abrasion on the tire surface takes place at an offset point, ie the position of the grinding wheel in relation to the tire tread is changed by changing the angle setting of the grinding wheel with respect to the tire tread. If the radial force fluctuations are reduced to within the tolerance range, ISt ₁ , the radial force fluctuations are compensated for in the same way.

In FIG. 2, the static lateral forces P ₁ and P ₀ determined in the two measurement runs in different directions are plotted over time. P- is the static side force in one direction of rotation and P _{2 is} the static side force in the other direction of rotation. The stored measured values are compared with one another in a comparison device and a decision is made as to whether compensation is to be carried out.

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If, for example, P ₁ = - P ₀ , then lsi the Komiseffeki = 0. Ee then no compensation needs to be carried out. If P. f P ^ ₅ , one-sided ablation must be carried out over the entire reuenumiang in the respective shoulder area. This removal causes a level shift of the static lateral force zero line, the distance α indicated in the figure being retained. There is thus only a change in the amount of P- and P ", so that a change in the cone effect is caused and detected due to the setting of the sign.

Through constant measurement and checking during the removal process the corresponding effect is continuously checked, without having to measure again in two directions. Furthermore, one can add both values to a comparator, which then the removal process ended when z. B. P. »- P and Fj.», Respectively. - kP » with O- ^ k ^ l, where the factor k is given as the limit value »,

The device suitable for carrying out the method according to the invention is shown as a block diagram in FIG. For the A two-component load cell 1 is used to measure the radial forces as well as measuring amplifiers 3, 4 for each component, a downstream adder 7 and a subsequent separating device for the static ones Components are provided, lh in the same way a two-component load cell 2, two is also used for measuring the lateral forces Measuring amplifiers 5 and 6 for each component, a downstream? Summing 8 and then a separator for the static components provided «'...

The outputs of the separators θ and 10 are to a Bawdier he placed where the tan α from the vectors of the side force cliwaG-

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kung and the radial force fluctuation SKS and RKS is determined. At the output of the divider there is a memory 12. At the output of the memory 12 are limit value preselectors 13 .. 14 _? 15 for different limit values tan Gp tan α «, tan α«. The outputs of this limit value preselector are connected to a logic device 16. A servo control 17 of the removal device is connected to the outputs of the logic device 16.

In addition, a peak value rectifier is at an output of the separating device 10 18 connected; at the outputs of which a memory 19 is located. The memory 19 is in turn with the logic device 16 connected.

The function of the device shown in Fig. 3 is as follows: The dispensed from the two-component load cells 1 and 2, the Tensions corresponding to the respective forces are generated in the measuring amplifiers 3, 4, 5, 6 amplified, then in the summers 7, 8 summed up and in the separation devices 19, the static components, z. B. in the radial direction the load and in the lateral direction the so-called cone or angle effect components, separated. The values for the vectors of the radial force fluctuations and the lateral force fluctuations, which are at the outputs of the separation devices 9 and 10 are fed to the divider 11, where the corresponding tan α is determined. This value is stored in memory 12 and also fed to limit value preselectors 13, 14, 15. Depending on the preset limit value preselection for tan α, the servo control 17 for the removal unit receives it via the logic device 16 the command to remove material according to radial or lateral signals to undertake.

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The peak value rectifier 18 provides the information as to whether the left or right tire shoulder has to be acted upon during a lateral removal process. This is done depending on the direction of the vector for the lateral force fluctuations SKS, the corresponding positive one or provides negative voltage values which are supplied to the logic device 16 via the memory 19.

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Claims (10)

Claims 1. / Procedure for reducing or eliminating irregularities on motor vehicle tires, in which forces are measured when the loaded tire is stationary or rolling and depending on the angular positions and the magnitude of the forces and the determined moments, material is removed from the tire, characterized in that both the lateral and the radial forces are measured and that as a function of these Forces both in the lateral direction as. also in the radial direction oriented material removal takes place. 2. The method according to claim 1, characterized in that as a function the material removal depends on the vector size and the vector angle of the instantaneous values of the radial and lateral force fluctuations is carried out separately and differently. 3. The method according to claim 1 or 2, characterized in that depending on the direction of the vector sum of the lateral and radial forces, either one material removal oriented in the radial or lateral direction takes place, which is opposite to the other Direction is reinforced. 4. The method according to any one of claims 1-3, characterized in, that with increased material removal in one direction this material removal takes place twice as much as in the other direction. 5. The method according to claim 4, characterized in that after each or after every second rotation of the tire approximately twice increased material removal takes place. 6151 509812/0066 6. The method according to claim 1, characterized in that the material removal takes place in one of the two directions (lateral, radial) until the force fluctuations in the other direction become one experience significant influence as a result of the material removal and that with a significant change in the force fluctuations in the other Direction the material removal takes place at a correspondingly offset point on the motor vehicle tire. 7. The method according to claim 1, characterized in that the ablations take place according to the first to nth order harmonics. 8. Device for reducing or eliminating irregularities on motor vehicle tires with force measuring devices and material removal means, in particular in the form of grinding devices, which are controlled by the force measuring devices for performing one of the methods according to claims 1-7, thereby characterized in that two removal devices, in particular grinding devices, are provided which are applied to the tire shoulders can be attached and can be controlled separately according to the determined instantaneous values of the lateral and radial forces. 9. Apparatus according to claim 8, characterized in that the angular position of the grinding devices relative to the tire shoulder is changeable. 10. The device according to claim 8, characterized in that the removal devices at any points on the tire circumference are provided. ⁶¹⁵¹ 5Q9812 / 0066